不同时间格式转换问题_python2

def unix_to_cst(data):
    """2019-03-17 11:00:00 --> Sun, 17 Mar 2019 11:00:00 GMT+0800 (CST)
    :param data:
    :return:
    """
    try:
        data = str(data)
        if len(data) > len("2019-03-17 11:00:00"):
            data = data[:len("2019-03-17 11:00:00")]
        dd = datetime.datetime.strptime(data, "%Y-%m-%d %H:%M:%S")
        GMT_FORMAT = '%a, %d %b %Y %H:%M:%S GMT'
        return dd.strftime(GMT_FORMAT)
    except Exception as e:
        return None


print unix_to_cst("2019-03-17 11:00:00")